A very promising extension. There are only two things which are bugging me:

1) Since the tags result in readable feeds, they should be treated as such and should be shown as folders with unread counts.
At present they show a kind of unwieldy result list and one needs to manually monitor them for new content.
That behaviour sadly makes tags more of a chore than a convenience.

2) One cannot turn off the boldly presented unread count displayed at the extension icon.
This assumes that everyone wants to know, how many unread items there are, all the time - which is simply not realistic.
I'm perfectly content with knowing exactly, how many unread items there are, after opening the extensions main window.